Turkish hackers reportedly targeted the Vatican’s Web site on Monday after Pope Francis referred to the mass killings of Armenians by Turks as a “genocide,” according to reports.

Vatican.va was knocked offline after a cyber attack Monday night, according to reports, but was back online by Tuesday morning.

A Turkish hacker posted on Twitter taking credit and demanding an apology.

The Vatican has been targeted by hackers in the past. Anonymous, an international hacking group, took down the Catholic Church’s main Web site in 2012. The group has made repeated attempts to take down the church’s website.

The attack comes as pope called the 1915 killings of up to 1.5 million Armenians by Turks a “genocide,” and not just any genocide but “the first genocide of the 20th century.”

He spoke during a Sunday mass to commemorate the 100th anniversary of the tragedy. Turkey reacted furiously and recalled its ambassador to the Vatican. American presidents have tiptoed around the word “genocide,” using other words like “Great Catastrophe.”

Turkish President Recep Tayyip Erdoğan condemned the pope for his comments, warning him to not describe the mass killings of Ottoman Armenians as “genocide.”

“Whenever politicians, religious functionaries assume the duties of historians, then delirium comes out, not fact. Hereby, I want to repeat our call to establish a joint commission of historians and stress we are ready to open our archives. I want to warn the pope to not repeat this mistake and condemn him,” Erdoğan said.

A request for comment from the Vatican was not immediately returned Tuesday.

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